SD_SARG3
New Member
Hi, this will be my first post on this forum. I have a very sick 1998 Ford Expedition XLT with a 4.6L engine.
I bought her roughly three months ago with an engine misfire caused by a bad coil pack. I have since replaced that coil pack and the vehicle ran fine for roughly 3,000 miles. Now she is experiencing very rough idle with sluggish performance off the line.
Initial Code Results were P0171 and P0174 which are lean conditions in banks 1 and 2. There was also a code for misfires in cylinders 1, 3 and 8. All these codes have however have not come back after performing the tasks below. The only code now showing in the system is the code P1131 - "Lack Of HO2S11 Switch Sens Indicates Lean".
I have read many forums and done many diagnostics that have lead me to swapping parts out and cleaning parts as well. So here is a list of components that have been cleaned or replaced:
-Spark Plugs (Replaced)
-Coil Wires (Replaced)
-Throttle Body Assembly (Cleaned)
-Throttle Body Assembly Gaskets (Replaced / 4 Total Gaskets)
-PCV Hose Leading to Service Port (Replaced)
-Fuel Filter (Replaced)
-Idle Air Control Valve (Cleaned)
-Mass Air Flow Sensor (Cleaned)
-Fuel Injectors (Cleaned)
I also have done a few tests on the system.
-Fuel Pressure (35-40psi - dependent of RPM)
-Fuel Injector Resistance (14.1-14.4 Ohms)
-Upstream O2 Sensors (Tested Good with Induced Rich Condition)
-Vacuum Pressure Leak with Carb Cleaner while Cold
(Found Leaks with Gaskets - Replaced)
I have also tested the EGR valve with source vacuum from the engine. There was almost no change in engine performance in either cold or hot engine tests. Would these results indicate a bad EGR Valve? If not, what other problems could be happening.
Any ideas or experience with these issues would be greatly appreciated.
I bought her roughly three months ago with an engine misfire caused by a bad coil pack. I have since replaced that coil pack and the vehicle ran fine for roughly 3,000 miles. Now she is experiencing very rough idle with sluggish performance off the line.
Initial Code Results were P0171 and P0174 which are lean conditions in banks 1 and 2. There was also a code for misfires in cylinders 1, 3 and 8. All these codes have however have not come back after performing the tasks below. The only code now showing in the system is the code P1131 - "Lack Of HO2S11 Switch Sens Indicates Lean".
I have read many forums and done many diagnostics that have lead me to swapping parts out and cleaning parts as well. So here is a list of components that have been cleaned or replaced:
-Spark Plugs (Replaced)
-Coil Wires (Replaced)
-Throttle Body Assembly (Cleaned)
-Throttle Body Assembly Gaskets (Replaced / 4 Total Gaskets)
-PCV Hose Leading to Service Port (Replaced)
-Fuel Filter (Replaced)
-Idle Air Control Valve (Cleaned)
-Mass Air Flow Sensor (Cleaned)
-Fuel Injectors (Cleaned)
I also have done a few tests on the system.
-Fuel Pressure (35-40psi - dependent of RPM)
-Fuel Injector Resistance (14.1-14.4 Ohms)
-Upstream O2 Sensors (Tested Good with Induced Rich Condition)
-Vacuum Pressure Leak with Carb Cleaner while Cold
(Found Leaks with Gaskets - Replaced)
I have also tested the EGR valve with source vacuum from the engine. There was almost no change in engine performance in either cold or hot engine tests. Would these results indicate a bad EGR Valve? If not, what other problems could be happening.
Any ideas or experience with these issues would be greatly appreciated.
